use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn get_line() -> String {
    let stdin = stdin();
    let mut line = String::new();
    stdin.lock().read_line(&mut line).expect("io error.");
    line.trim().to_string()
}

#[allow(dead_code)]
fn cast<T: FromStr>(s: &str) -> T {
    s.parse().ok().expect("parse error.")
}

#[allow(dead_code)]
fn get_vec<T: FromStr>() -> Vec<T> {
    (&get_line()).split(' ').map(cast::<T>).collect()
}


/* ---------- ここまでテンプレ ---------- */


fn main() {
    let mut data: Vec<(u64, usize)> = Vec::new();
    for i in 0..3 {
        data.push((cast(&get_line()), i));
    }

    data.sort();
    for (_, i) in data.iter().rev() {
        println!("{}", ((*i as u8) + ('A' as u8)) as char);
    }
}